In a spiral oven or freezer the conveyor belt in the forward run follows a well-defined spiral path such that the conveyor belt turns around a central tower/drum on the inside and on the outside the belt is limited by a guide rail or similar device. This causes the side flex conveyor belt to be exposed to tension along the outside edge of the belt whereas the inside edge of the belt which is lying against the drum is substantially slack, i.e. is not exposed to any tensile forces. The belt is driven, typically by friction between the inside edge of the belt and a drum arranged centrally in the spiral device. Due to the position of the drive on the inside of the spiral path, the flexible conveyor belt will collapse on the inside in order to transfer the drive force to the entire belt width. In practice this causes wobbling and bending especially of the inside portion of the belt and at the same time causes tension in the outside of the belt. The buckling occurs due to the fact that these types of conveyor belts are constructed from a plurality of interconnected modular belt links where the connection is created in a hinge-like manner by a hinge or connection pin inserted laterally through overlapping/superposed apertures in eye parts on each modular belt link. The hinge connection allows the belt links to bend out of the plane of the conveyor belt. As the force on the inside of the conveyor belt is substantially larger than the distributed force along the outside edge there will be an increased tendency to a buckling along the inside edge. As the width of the conveyor belt is assembled by a plurality of independent modular belt links which are only interconnected by the connection pin, the connection pin will also be exposed to forces perpendicular to the plane of the conveyor.
In the art various attempts have been made in order to address such problems. One example is EP 1377408 in which a radius limit adjuster is disclosed. The radius limit adjuster is inserted between adjacent belt links proximate a side edge of the conveyor belt. In order to fit a conveyor belt in a spiral device application, it is necessary to select a conveyor having a basic radius, and then fit the limiter to the belt. For other turning radiuses it is necessary to select an alternative basic belt having a different turning radius etc. The limiter is therefore not universal, and furthermore does not provide force distribution across the conveyor belt, whereby buckling and other detrimental occurrences will arise.